This is a family of bacterial and archaeal PINc domains. PIN domains are characterised by the conservation of three acidic residues, possibly four, an Asp at residue 13, a Glu at 63, and then Asps at 172 and 194 in UniProtKB:Q58360. Family members include Homologs of Aquifex RNase P (HARP) proteins [2].

1: The PIN-domain ribonucleases and the prokaryotic VapBC toxin-antitoxin array. Arcus VL, McKenzie JL, Robson J, Cook GM; Protein Eng Des Sel. 2011;24:33-40. PMID:21036780

2: Comprehensive classification of the PIN domain-like superfamily. Matelska D, Steczkiewicz K, Ginalski K; Nucleic Acids Res. 2017;45:6995-7020. PMID:28575517